1. Field of the Invention
The present invention relates to the use of pyrazole derivatives of the formula I ##STR1## or their acid addition salts as nitrification inhibitors, where the radicals R.sup.1, R.sup.2, R.sup.3 and R.sup.4 have the following meanings:
R.sup.1, R.sup.2 and R.sup.3 are halogen, nitro, hydrogen, C.sub.1 - to C.sub.20 -alkyl, C.sub.3 - to C.sub.8 -cycloalkyl, C.sub.5 - to C.sub.20 -aryl or alkylaryl, it being possible for these 4 radicals to be monosubstituted or disubstituted by halogen and/or hydroxyl PA1 R.sup.4 is either PA1 R.sup.7 is a carboxyl radical or a carboxy-(C.sub.1 - to C.sub.3 -alkyl) radical or a functional derivative of these groups or PA1 R.sup.10 is hydrogen or a poly-(C.sub.2 - to C.sub.4 -alkylene oxide) radical whose terminal hydroxyl group can be etherified by an aliphatic C.sub.1 - to C.sub.10 -alkohol or esterified by a C.sub.1 - to C.sub.10 -carboxylic acid. PA1 excessively low activity based on the application rate; PA1 excessively low stability against hydrolysis, whereby the duration of action in the soil and the stability on storage is reduced. This relates especially to pyrazole derivatives such as N-glyoxylpyrazoles and N-hydroxymethylpyrazoles, and mineral acid salts of pyrazoles; PA1 excessively high toxicity or ecotoxicity; PA1 only accessible by complicated preparation processes (eg. N-hydroxypyrazoles); PA1 excessively low absorption of the compounds in the soil, whereby they are rapidly leached; PA1 excessively high volatility. This results in the compounds being easily given off from the soil into the atmosphere unless the compounds are introduced into the soil using technically complicated processes (eg. by probe). PA1 R.sup.2 is halogen and PA1 R.sup.4 is a radical having the formula II, the substituents R.sup.5, R.sup.6 and R.sup.7 having the meanings indicated for the-formula I, PA1 R.sup.2 is halogen PA1 R.sup.1 l is hydrogen, C.sub.1 - to C.sub.20 -alkyl, C.sub.3 - to C.sub.8 -cycloalkyl or C.sub.1 - to C.sub.10 -acyl PA1 R.sup.12 is hydrogen or methyl PA1 x is 1 to 10 PA1 a) R.sup.4a radicals having the formula II ##STR7## where R.sup.5 and R.sup.6 are hydrogen, C.sub.1 - to C.sub.20 -alkyl which can be monosubstituted or disubstituted by halogen and/or hydroxyl, a carboxyl group, a carboxymethyl group or a functional derivative of the two last-mentioned groups, and PA1 b) R4b radicals having the formula III ##STR8## where R.sup.8 and R.sup.9 are C.sub.1 - to C.sub.20 -alkyl, C.sub.3 - to C.sub.8 -cycloalkyl, C.sub.5 - to C.sub.20 -aryl or alkylaryl, it being possible for these 4 radicals to be monosubstituted or disubstituted by halogen and PA1 R.sup.10 is hydrogen or a poly-(C.sub.2 - to C.sub.4 -alkylene oxide) radical whose terminal hydroxyl group can be etherified by an aliphatic C.sub.1 - to C.sub.10 -alkohol or esterified by a C.sub.1 - to C.sub.10 -carboxylic acid. PA1 unsubstituted alkyl radicals, in particular C.sub.1 - to C.sub.6 -alkyl radicals such as methyl, ethyl and propyl and also hydrogen. In addition, carboxymethyl groups or functional groups of the carboxymethyl groups are especially suitable. PA1 R.sup.5 -hydrogen PA1 R.sup.6 -hydrogen, methyl, a carboxyl group, a carboxymethyl group or a functional derivative of the two last-mentioned groups PA1 R.sup.7 -a carboxymethyl group, a 1-carboxyethyl group or functional derivatives of these groups. PA1 R.sup.5 hydrogen, R.sup.6 carboxyl, R.sup.7 carboxymethyl PA1 R.sup.5 hydrogen, R.sup.6 hydrogen, R.sup.7 carboxymethyl PA1 R.sup.5 hydrogen, R.sup.6 hydrogen, R.sup.7 1-carboxyethyl PA1 R.sup.12 is hydrogen or methyl PA1 x is 1 to 10, preferably 2 to 6. PA1 R.sup.x has the same meanings as R.sup.1 PA1 R.sup.y has the same meanings as R.sup.2 PA1 R.sup.z has the same meanings as R.sup.3 PA1 R.sup.x has the same meanings as R.sup.3 PA1 R.sup.y has the same meanings as R.sup.2 PA1 R.sup.z has the same meanings as R.sup.1 PA1 the radical R.sup.14 is a carboxyl group or a functional derivative of a carboxyl group and PA1 the radical R.sup.15 is hydrogen or methyl.
a) a radical R.sup.4a having the formula II ##STR2## where R.sup.5 and R.sup.6 are hydrogen, C.sub.1 - to C.sub.20 -alkyl which can be monosubstituted or disubstituted by halogen and/or hydroxyl, a carboxyl group, a carboxymethyl group or a functional derivative of the two last-mentioned groups, and PA2 b) a radical R.sup.4b having the formula III ##STR3## where R.sup.8 and R.sup.9 are hydrogen, C.sub.1 - to C.sub.20 -alkyl, C.sub.3 - to C.sub.8 -cycloalkyl, C.sub.5 - to C.sub.20 -aryl or alkylaryl, it being possible for these 4 radicals to be monosubstituted or disubstituted by halogen and PA2 R.sup.7 is a carboxyl radical or a carboxy-(C.sub.1 - to C.sub.3 -alkyl) radical or a functional derivative of these radicals or
The invention furthermore relates to novel pyrazole derivatives which are suitable for this intended use, processes for their preparation and fertilizer mixtures which contain such pyrazole. derivatives.
2. Description of the Background
In order to make available to plants the nitrogen needed by them, they are fertilized, as is known, with ammonium compounds. Ammonium compounds, however, are microbially converted to nitrate in the soil in a relatively short time (nitrification).
Because nitrate is leached from the soil more easily than ammonium and the leached portion is no longer available for plant nutrition, however, rapid nitrification is undesirable. In order that the fertilizer is utilized better, it was therefore proposed to add nitrification inhibitors to the soil.
EP-A 474 037 discloses 3-methylpyrazole derivatives in which one nitrogen atom of the pyrazole ring carries a methyl, cycloalkyl, aryl or aralkyl radical. It is proposed to use these compounds as intermediates for the preparation of pharmaceutical products or crop protection agents.
U.S. Pat. No. 3,635,690 discloses the employment of various pyrazole derivatives for the inhibition of nitrification. In the pyrazole derivatives proposed, the nitrogen atoms in the pyrazole ring do not carry any substituents or one of the nitrogen atoms carries a saturated or unsaturated C.sub.1 - to C.sub.3 -hydrocarbon radical. One or more carbon atoms in the pyrazole ring can be substituted by hydrocarbon radicals which may carry halogens as substituents. Examples of these are 3-methylpyrazoles such as 4-chloro-3-methylpyrazole.
U.S. Pat. No. 4,969,946 also describes the use of pyrazole derivatives as nitrification inhibitors. In these derivatives, the nitrogen atoms in the pyrazole ring are unsubstituted, and several of the ring carbon atoms are substituted by halogen or methyl.
DE-A 3 704 359 relates to compositions which inhibit nitrification. As active compound, they contain pyrazole derivatives which, on one nitrogen atom of the pyrazole ring, carry a radical of the formula ##STR4##
where R' is a substituted or unsubstituted organic radical or a hydroxyl radical.
Further nitrification inhibitors are disclosed in EP-A 0 160 804. They are pyrazole derivatives in which a nitrogen atom in the pyrazole ring carries a substituted oxycarbonyl, sulfinyl or sulfonyl radical.
DE-A 4 018 395 mentions derivatives of 1-cyano-3-methylpyrazole and its acid addition products or coordination compounds as nitrification inhibitors.
SU-A 1 470 737 discloses N-hydroxymethyl derivatives of pyrazole.
These active compounds are still not entirely satisfactory as nitrification inhibitors as they have one or more of the following disadvantages: